1. Field of the Invention
The present invention relates generally to a trailer hitch for providing safe and secure coupling of a trailer to a towing vehicle and, more particularly, is concerned with apparatus associated with the hitch for detecting when the components of the hitch have started to uncouple and for signaling the operator of the same.
2. Background of the Prior Art
A conventional trailer hitch is composed of two basic components, a ball member connected on the rear end of an attachment plate mounted to the towing vehicle and a socket member connected to the forward end of the towed trailer. In addition to the ball and socket members, a latch mechanism is ordinarily mounted adjacent to the socket member and is actuatable, once the socket member has been placed or seated on the ball member, to couple the two together. Typically, the socket member includes a part movable by the latch mechanism to a locking position which prevents uncoupling of the socket member from the ball member.
While the socket member is thusly "locked" on the ball member, the coupling must permit lateral pivoting of the socket and ball members relative to one another through a wide angle for accommodating turning of the towing vehicle relative to the trailer. Also, the coupling must permit limited vertical pivoting of the socket and ball members relative to one another for accommodating uneven terrain. In short, although a firm and reliable connection must be maintained between the members, the two members must be permitted to rotate and pivot freely.
Trailer hitch components of the type described are inherently subject to abuse, corrosion and wear due to various factors, such as highway jarring and vibration and exposure to weather, which can result in defective operation of the latching mechanism and uncoupling during use. Also, the operator could fail to properly actuate the latching mechanism to securely couple the socket member to the ball member or could forget to do so altogether. The consequences of the trailer uncoupling from the vehicle during towing on the highway are oftentimes catastrophic in terms of personal injury to others on the highway as well as the damage to the trailer. The operator of the towing vehicle is normally unaware that the trailer hitch components are not securely coupled or are starting to uncouple until the trailer actually breaks loose of the towing vehicle.
Various safety devices have been proposed in the prior art to sense or detect uncoupling of the trailer hitch components and alert the towing vehicle operator. Representative of the prior art are the devices disclosed in U.S. patents to Brown et al (U.S. Pat. No. 3,047,839), Miller (U.S. Pat. No. 3,479,057), Ellis et al (U.S. Pat. No. 3,792,432) and Quilici et al (U.S. Pat. No. 3,710,370). While many of these devices would appear to operate reasonably well and generally achieve their objectives under the range of operating conditions for which they were designed, most seem to embody shortcomings which make them less than an optimum safety device. Some devices have components which are exposed to inadvertent damaging contact during guiding and hitching of the socket member to the ball member. Other devices deploy their components where they are subject to corrosion and the accumulation of dirt and other foreign matter which make them susceptible to malfunction. Still other devices, being composed of a multiplicity of parts, are complex and costly to manufacture. Further, each time the socket member is hitched to the ball member, some of the devices require several setup steps in addition to the step of latching the socket member to the ball member. In other words, activation of the safety device is not automatic with coupling of the hitch members. Finally, some devices will only work with a socket member within a limited range of structural configurations and therefore do not have universal application to all hitch configurations.
Consequently, a need still exists for a safety device which is relatively inexpensive, simple in construction and operation, adaptable for use on a variety of hitch socket configuration and not deployed in a location where it is apted to become damaged.